Steam has been used in many different methods for the recovery of oil from subterranean, viscous oil-containing formations. The two most basic processes using steam for the recovery of oil includes a "steam drive" process and "huff and puff" steam processes. Steam drive involves injecting steam through an injection well into a formation. Upon entering the formation, the heat transferred to the formation by the steam lowers the viscosity of the formation oil, thereby improving its mobility. In addition, the continued injection of the steam provides the drive to displace the oil toward a production well from which it is produced. Huff and puff involves injecting steam into a formation through a well, stopping the injection of steam, permitting the formation to soak and then back producing oil through the original well.
Steam flooding operations for recovering heavy oil utilizing propane- or diesel-fired downhole steam generators are described in the articles "Steam Generators Work Long Periods Downhole", OIL AND GAS JOURNAL, July 5, 1982, pp. 76 and 78, and "West Coast EOR Project Results Discouraging", OIL AND GAS JOURNAL, Aug. 9, 1982, page 82.
Applicants' copending application filed June 28, 1983, Ser. No. 508,705, now U.S. Pat. No. 4,478,280 relates to a viscous oil-containing formation by a steam flooding technique wherein steam is generated in a downhole steam generator located in an injection well by spontaneous combustion of a pressurized mixture of a water-soluble fuel such as sugars and alcohols dissolved in water or a stable hydrocarbon fuel-in-water emulsion and substantially pure oxygen.
In addition, many producing formations being steam flooded contain a certain amount of swelling clays in the form of a bentonite or montmorillonite clay, which upon swelling, reduces the permeability of the formation. Various methods are known for avoiding clay swelling such as use of low-grade steam containing dissolved salts described in U.S. Pat. No. 3,237,692 and treating wet steam with sodium chloride, guanidine hydrochloride, or other surface active agents as disclosed in U.S. Pat. No. 3,476,183.
The present invention provides an improved steam flood recovery process wherein steam is generated in a downhole generator located in the injection well adjacent the oil-containing formation by spontaneous combustion of a pressurized mixture of a water-soluble fuel dissolved in water or a hydrocarbon fuel-in-water emulsion containing an anti clay-swelling agent with substantially pure oxygen.